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| United States Patent |
5,198,573
|
|
Deweerdt
, et al.
|
March 30, 1993
|
Diesters of hexene-1,6-dioic acids produced from
1,2-dialkoxy-3-butenes/co
Abstract
Diesters of hexene-1,6-dioic acids are prepared by reacting at least one
1,2-dialkoxy-3-butene with carbon monoxide in the presence of a
catalytically effective amount of a palladium-based catalyst and a halogen
compound, in liquid phase, at elevated temperature and at superatmospheric
pressure.
| Inventors:
|
Deweerdt; Helene (Lyon, FR);
Jenck; Jean (Chassieu, FR);
Kalck; Philippe (Castanet Tolosane, FR);
Mutez; Sylvain (Irigny, FR);
Perron; Robert (Charly, FR)
|
| Assignee:
|
Rhone-Poulenc Chimie (Courbevoie, FR)
|
| Appl. No.:
|
762402 |
| Filed:
|
September 19, 1991 |
Foreign Application Priority Data
| Current U.S. Class: |
560/204; 560/190; 562/550; 562/595 |
| Intern'l Class: |
C07C 067/37 |
| Field of Search: |
560/204,190
562/550,595
|
References Cited
U.S. Patent Documents
| 4611082 | Sep., 1986 | Chan et al. | 560/204.
|
| 4925973 | Mar., 1990 | Deweerdt et al. | 560/204.
|
| Foreign Patent Documents |
| 0217407 | Aug., 1987 | EP.
| |
| 0347340 | Dec., 1989 | EP.
| |
Primary Examiner: Dees; Jose G.
Assistant Examiner: Clarke; Vera C.
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis
Claims
What is claimed is:
1. A process for the preparation of a diester of a hexene-1,6-dioic acid,
comprising reacting at least one 1,2-dialkoxy-3-butene with carbon
monoxide in the presence of a catalytically effective amount of a
palladium-based catalyst and a halogen compound, in liquid phase, at
elevated temperature and at superatmospheric pressure.
2. The process as defined by claim 1, wherein one of said at least one
1,2-dialkoxy-3-butene is 1,2-dimethoxy-3-butene.
3. The process as defined by claim 1, wherein one of said at least one
1,2-dialkoxy-3-butene is 1,2-diethoxy-3-butene.
4. The process as defined by claim 1, said at least one
1,2-dialkoxy-3-butene comprising an admixture thereof with a
1,4-dialkoxy-2-butene.
5. The process as defined by claim 1, said halogen compound comprising an
ionic chloride, the cation of which being selected from among:
(a) an alkali metal cation,
(b) an alkaline earth metal cation, and
(c) a quaternary onium cation of one of the Group VB elements nitrogen and
phosphorus, such element being tetracoordinated to carbon atoms, with the
proviso that the nitrogen may be coordinated to two pentavalent phosphorus
atoms.
6. The process as defined by claim 5, said halogen compound comprising a
quaternary onium chloride of one of the Group VB elements nitrogen and
phosphorus, such element being tetracoordinated to carbon atoms, with the
proviso that the nitrogen may be coordinated to two pentavalent phosphorus
atoms.
7. The process as defined by claim 6, said quaternary onium cation having
one of the following formulae (I) to (V):
##STR4##
in which A is a nitrogen or phosphorus atom; R.sub.1, R.sub.2, R.sub.3,
R.sub.4, which may be identical or different, are each a linear or
branched having from 1 to 16 carbon atoms, unsubstituted or substituted by
a phenyl, hydroxyl, halo, nitro, alkoxy or alkoxycarbonyl group, a linear
or branched alkenyl radical having from 2 to 12 carbon atoms, an aryl
radical having from 6 to 10 carbon atoms, unsubstituted or substituted by
one or more alkyl radicals having from 1 to 4 carbon atoms, alkoxy,
alkoxycarbonyl or halo radicals, with the proviso that two of said
radicals R.sub.1 to R.sub.4 may together form a linear or branched
alkylene, alkenylene or alkadienylene radical having from 3 to 6 carbon
atoms; R.sub.5, R.sub.6, R.sub.7, R.sub.8, which may be identical or
different, are each a linear or branched alkyl radical having from 1 to 4
carbon atoms, with the proviso that the radicals R.sub.7 and R.sub. 8 may
together form an alkylene radical having from 3 to 6 carbon atoms, and
with the further proviso that the radicals R.sub.6 and R.sub.7 or R.sub.8
may together form an alkylene, alkylene or alkadienylene radical having 4
carbon atoms and constituting a nitrogenous heterocyclic ring with N;
R.sub.9 is a linear or branched alkyl radical having from 1 to 4 carbon
atoms or a phenyl radical; R.sub.10 is a linear or branched alkyl radical
having from 1 to 4 carbon atoms, the same as or different from R.sub.9, a
linear or branched alkenyl radical having from 2 to 12 carbon atoms; n is
an integer greater than or equal to 1 and less than or equal to 10;
R.sub.11 is an aryl radical having from 6 to 10 carbon atoms,
unsubstituted or substituted by one or more alkyl groups having from 1 to
4 carbons, alkoxy, alkoxycarbonyl or halo groups, R.sub.12 and R.sub.13,
which may be identical or different, have the definitions given above for
R.sub.1 to R.sub.4 ; and R.sub.14 to R.sub.16, which may be identical or
different, are each a hydrogen atom, a linear or branched radical having
from 1 to 16 carbon atoms, unsubstituted or substituted or by a phenyl,
hydroxyl, halo, nitro, alkoxy or alkoxycarbonyl group, a linear or
branched alkenyl radical having from 2 to 12 carbon atoms, an aryl radical
having from 6 to 10 carbon atoms, unsubstituted or substituted by one or
more alkyl radicals having from 1 to 4 carbon atoms, alkoxy,
alkoxycarbonyl or halo radicals, with the proviso that the radicals
R.sub.14 and R.sub.15 may together form a linear or branched alkylene,
alkenylene or alkadienylene radical having from 3 to 6 carbon atoms, to
constitute an aromatic ring with the two adjoining carbon atoms of the
imidazole ring.
8. The process as defined by claim 7, said quaternary onium cation having
the formula (I) in which A is phosphorus, and R.sub.1, R.sub.2, R.sub.3
and R.sub.4, which may be identical or different, are each a linear or
branched alkyl radical having from 1 to 8 carbon atoms, a phenyl or
4-methylphenyl radical.
9. The process as defined by claim 1, said halogen compound comprising
tetrabutylphosphonium chloride.
10. The process as defined by claim 1, said halogen compound comprising an
alkali or alkaline earth metal chloride.
11. The process as defined by claim 1, said halogen compound comprising
lithium chloride.
12. The process as defined by claim 10, carried out in an aprotic and basic
polar solvent.
13. The process as defined by claim 12, said solvent having the formula
(VI):
##STR5##
in which R.sub.a, R.sub.b and R.sub.c, which may be identical or
different, are each an alkyl radical, a cycoalkyl radical, an aralkyl
radical or a monocyclic aryl radical having up to 10 carbon atoms, with
the proviso that two of the radicals R.sub.a, R.sub.b or R.sub.c or may
together form a single divalent radical (CH.sub.2).sub.y, wherein y is an
integer ranging from 2 to 12, and with the further proviso that R.sub.a
may be a radical:
##STR6##
in which R.sub.d and R.sub.c, which may be identical or different, are
each an alkyl radical having up to 4 carbon atoms.
14. The process as defined by claim 12, said solvent comprising at least
10% by volume of the reaction mixture.
15. The process as defined by claim 12, said solvent comprising
N-methyl-2-pyrrolidone.
16. The process as defined by claim 5, the molar ratio of chloride anion to
palladium ranging from 3 to 100.
17. The process as defined by claim 1, the concentration of palladium in
the reaction mixture ranging from 10.sup.-3 to 1 mol/l.
18. The process as defined by claim 1, carried out at a temperature ranging
from 50.degree. to 180.degree. C.
19. The process as defined by claim 1, carried out under a pressure greater
than or equal to 20 bar and less than or equal to 250 bar.
20. The process as defined by claim 19, carried out under a pressure
ranging from 90 to 180 bar.
21. The process as defined by claim 1, said palladium-based catalyst
comprising palladium chloride.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the preparation of diesters of
hexene-1,6-dioic acids. Such diesters can be facilely hydrogenated into
the corresponding diesters of adipic acid, or adipates, which can in turn
be hydrolyzed to form adipic acid. Adipic acid, one of the raw materials
for nylon 66, is currently produced in vast amounts and, because of this
fact alone, any novel synthesis for this diacid and/or derivatives thereof
would be of fundamental interest.
The present invention especially relates to the preparation of diesters of
3-hexene-1,6-dioic acid by reacting carbon monoxides with at least one
1,2-dialkoxy-3-butene in the presence of a palladium-based catalyst.
2. Description of the Prior Art
It is known to this art, per Imamura and Tsuji, Tetrahedron. vol. 25, p.
4187-4195 (1969), to prepare diesters of 3-hexene-1,6-dioic acid by
reacting carbon monoxide with 1,4-diethoxy-2-butene in ethanol, in the
presence of palladium and chloride.
1,2-Diethoxy-3-butene is mentioned as a coproduct, assumed to originate by
an allyl rearrangement of 1,4-diethoxy-2-butene.
U.S. Pat. No. 4,611,082 describes dicarbonylating a 1,4-dialkoxy-2-butene
in a polar, aprotic and nonbasic solvent, at 80.degree. to 140.degree. C.
in the presence of a transition metal halide, palladium chloride being the
most effective.
This same type of reaction, starting with 1,4-dimethoxy-2-butene, is
described in detail in Journal of Molecular Catalysis, 53. pp. 417-432
(1989).
Over the course of research by the assignee hereof relating to the
preparation of dialkoxybutenes from 1,3-butadiene, it has been shown that,
in general, a mixture is produced containing especially the
1,4-dialkoxy-2-butene (predominant ether) and the 1,4-dialkoxy-3-butene,
these two diethers being relatively difficult to separate from each other.
SUMMARY OF THE INVENTION
A major object of the present invention is the provision of a novel process
for the preparation of diesters of 3-hexene-1,6-dioic acid, comprising
reacting carbon monoxide with at least one 1,2-dialkoxy-3-butene in the
presence of a palladium-based catalyst.
Briefly, the present invention features a process for the preparation of
diesters of 3-hexene-1,6-dioic acid, which comprises reacting carbon
monoxide with at least one dialkoxybutene in the presence of a
palladium-based catalyst and of a halogen compound, in liquid phase, at
elevated temperature and at a pressure greater than atmospheric pressure,
said at least one dialkoxybutene comprising a 1,2-dialkoxy-3-butene.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, by
"1,2-dialkoxy-3-butene" is intended a 3-butene disubstituted in positions
1 and 2 by identical or different, linear, branched or cyclic alkoxy
groups and having from 1 to 12 carbon atoms. The two alkoxy groups are
preferably identical and advantageously have from 1 to 4 carbon atoms.
1,2-Dimethoxy-3-butene and 1,2-diethoxy-3-butene are starting materials
which are particularly preferred according to the present invention.
In an advantageous embodiment of the process of the invention, the
1,2-dialkoxy-3-butene(s) is (are) used in the form of a mixture with the
1,4-dialkoxy-2-butene(s), in which they may represent a variable molar
fraction, for example from 5% to 99% of the said mixture.
Indeed, it has now surprisingly been found that the selectivity for the
desired linear diester (linear dicarbonylated product), when starting with
such branched diethers (1,2-dialkoxy-3-butene), whether employed alone or
mixed with the corresponding linear diethers, is sufficiently high that
the starting material may be a mixture of the branched diether and the
linear diether in the proportions in which they are present during the
stage of their preparation from 1,3-butadiene.
The process according to the present invention is carried out in the
presence of a catalytically effective amount of a palladium-based
catalyst.
Although the precise mechanism of the catalytically active species in the
subject reaction is not completely known, the various palladium compounds
and metallic palladium are assumed to be useful precursors in carrying out
the process of the invention.
Exemplary palladium sources for carrying out the process of the invention
include:
(i) metallic palladium, deposited, if appropriate, on a support substrate
such as charcoal, alumina or silica;
(ii) PdCl.sub.2, Pd(OAc).sub.2 ;
(iii) palladium salts or .pi.-allyl complexes in which the anion
coordinated to the Pd cation is selected from among the following anions:
carboxylates such as formate, acetate, propionate, benzoate,
acetylacetonate, halides such as Cl.sup.- and Br.sup.- and preferably
Cl.sup.-.
Palladium chloride is advantageously used.
The precise amount of catalyst to be used, which may vary over wide limits,
will primarily depend on a compromise between the desired efficiency and
the expenditure of catalyst, and the other reaction conditions. In
general, good results are obtained using a palladium concentration in the
reaction mixture ranging from 10.sup.-3 to 1 mol/l. Below 10.sup.-3 mol/l
the kinetics of the reaction are greatly diminished. Amounts of palladium
which are greater than 1 mol/l are inconvenient simply from the viewpoint
of economy. This concentration preferably ranges from 10.sup.-2 to 1 mol/l
.
The process according to the present invention is also carried out in the
presence of a halogen compound. Advantageously, an ionic chloride is used
in which the cation is selected from among:
(a) alkali metal cations,
(b) alkaline earth metal cations, and
(c) quaternary onium cations of a Group VB element of the Periodic Table
selected from nitrogen and phosphorus, said element being tetracoordinated
to carbon atoms, with the proviso that the nitrogen may be coordinated to
two pentavalent phosphorus atoms.
Also advantageously, the quaternary onium chloride will comprise a
quaternary onium cation corresponding to one of the following formulae (I)
to (V):
##STR1##
in which A is a nitrogen or phosphorus atom; R.sub.1, R.sub.2, R.sub.3,
R.sub.4, which may be identical or different, are each a linear or
branched alkyl radical having from 1 to 16 carbon atoms, optionally
substituted by a phenyl, hydroxyl, halo, nitro, alkoxy or alkoxycarbonyl
group; a linear or branched alkenyl radical having from 2 to 12 carbon
atoms, preferably from 4 to 8 carbon atoms, an aryl radical having from 6
to 10 carbon atoms, optionally substituted by one or more alkyl radicals
having from 1 to 4 carbon atoms, alkoxy, alkoxycarbonyl or halo radicals,
with the proviso that two of said radicals R.sub.1 to R.sub.4 may together
form a linear or branched alkylene, alkenylene or alkadienylene radical
having from 3 to 6 carbon atoms; R.sub.5, R.sub.6, R.sub.7, R.sub.8, which
may be identical or different, are each a linear or branched alkyl radical
having from 1 to 4 carbon atoms, with the proviso that the radicals
R.sub.7 and R.sub.8 may together form an alkylene radical having from 3 to
6 carbon atoms, and with the further proviso that the radicals R.sub.6 and
R.sub.7 or R.sub.6 and R.sub.8 may together form an alkylene, alkenylene
or alkadienylene radical having 4 carbon atoms and constituting a
nitrogenous heterocyclic ring with N; R.sub.9 is a linear or branched
alkyl radical having from 1 to 4 carbon atoms or a phenyl radical;
R.sub.10 is a linear or branched alkyl radical having from 1 to 4 carbon
atoms, the same as or different from R.sub.9, a linear or branched alkenyl
radical having from 2 to 12 carbon atoms, preferably from 4 to 8 carbon
atoms; n is an integer greater than or equal to 1 and less than or equal
to 10 and preferably less than or equal to 6; R.sub.11 is an aryl radical
having from 6 to 10 carbon atoms, optionally substituted by one or more
alkyl groups having from 1 to 4 carbons, alkoxy, alkoxycarbonyl or halo
groups; R.sub.12 and R.sub.13, which may be identical or different, have
the definitions given above for R.sub.1 to R.sub.4 ; and R.sub. 14 to
R.sub.16, which may be identical or different, are each a hydrogen atom, a
linear or branched alkyl radical having from 1 to 16 carbon atoms,
optionally substituted by a phenyl, hydroxyl, halo, nitro, alkoxy or
alkoxycarbonyl group, a linear or branched alkenyl radical having from 2
to 12 carbon atoms, preferably from 4 to 8 carbon atoms, an aryl radical
having from 6 to 10 carbon atoms, optionally substituted by one or more
alkyl radicals having from 1 to 4 carbon atoms, alkoxy, alkoxycarbonyl or
halo radicals, with the proviso that the radicals R.sub.14 and R.sub.15
may together form a linear or branched alkylene, alkenylene or
alkadienylene radical having from 3 to 6 carbon atoms, to constitute an
aromatic ring with the two adjoining carbon atoms of the imidazole ring.
The following cations are exemplary quaternary onium cations corresponding
to the formula I: Tetramethylammonium, Triethylmethylammonium,
Tributylmethylammonium, Trimethyl(n-propyl)ammonium, Tetraethylammonium,
Tetrabutylammonium, Dodecyltrimethylammonium, Methyltrioctylammonium,
Heptyltributylammonium, Tetrapropylammonium, Tetrapentylammonium,
Tetrahexylammonium, Tetraheptylammonium, Tetraoctylammonium,
Tetradecylammonium, Butyltripropylammonium, Methyltributylammonium,
Pentyltributylammonium, Methyldiethylpropylammonium,
Ethyldimethylpropylammonium, Tetradodecylammonium, Tetraoctadecylammonium,
Hexadecyltrimethylammonium, Benzyltrimethylammonium,
Benzyldimethylpropylammonium, Benzyldimethyloctylammonium,
Benzyltributylammonium, Benzyltriethylammonium, Phenyltrimethylammonium,
Benzyldimethyltetradecylammonium, Benzyldimethylhexadecylammonium,
Dimethyldiphenylammonium, Methyltriphenylammonium,
But-2-enyltriethylammonium, N,N-Dimethyltetramethyleneammonium,
N,N-Diethyltetramethyleneammonium, Tetramethylphosphonium,
Tetrabutylphosphonium, Ethyltrimethylphosphonium,
Trimethylpentylphosphonium, Octyltrimethylphosphonim,
Dodecyltrimethylphosphonium, Trimethylphenylphosphonium,
Diethyldimethylphosphonium, Dicyclohexyldimethylphosphonium,
Dimethyldiphenylphosphonium, Cyclohexyltrimethylphosphonium,
Triethylmethylphosphonium, Methyltri(isopropyl)phosphonium,
Methyltri(n-propyl)phosphonium, Methyltri(n-butyl)phosphonium,
Methyltri(2-methylpropyl)phosphonium, Methyltricyclohexylphosphonium,
Methyltriphenylphosphonium, Methyltribenzylphosphonium,
Methyltri(4-methylphenyl)phosphonium, Methyltrixylylphosphonium,
Diethylmethylphenylphosphonium, Dibenzylmethylphenylphosphonium,
Ethyltriphenylphosphonium, Tetraethylphosphonium,
Ethyltri(n-propyl)phosphonium, Triethylpentylphosphonium,
Hexadecyltributylphosphonium, Ethyltriphenylphosphonium,
n-Butyltri(n-propyl)phosphonium, Butyltriphenylphosphonium,
Benzyltriphenylphosphonium, (.beta.-Phenylethyl)dimethylphenylphosphonium,
Tetraphenylphosphonium, Triphenyl(4-methylphenyl)phosphonium,
Tetrakis(hydroxymethyl)phosphonium, Tetrakis(2-hydroxyethyl)phosphonium.
The following cations are exemplary of those of formula II:
N-Methylpyridinium, N-Ethylpyridinium, N-Hexadecylpyridinium,
N-Methylpicolinium.
The following cations are exemplary of those of formula III:
1,2-Bis(trimethylammonium)ethane, 1,3-Bis(trimethylammonium)propane,
1,4-Bis(trimethylammonium)butane, 1,3-Bis(trimethylammonium)butane.
The following cations are exemplary of those of formula IV:
Bis(triphenylphosphine)iminium, Bis(tritolylphosphine)iminium.
And the following cations are exemplary of those of formula V:
1-Methyl-3-methylimidazolium, 1-Methyl-3-ethylimidazolium,
1-Methyl-3-n-propylimidazolium, 1-Methyl-3-n-butylimidazolium,
1-Methyl-3-benzylimidazolium, 1-Methyl-2-methyl-3-ethylbenzimidazolium.
Advantageously, onium cations corresponding to the above formula (I) are
used in which A is phosphorus, and R.sub.1, R.sub.2, R.sub.3 and R.sub.4,
which may be identical or different, are each a linear or branched alkyl
radical having from 1 to 8 carbon atoms, a phenyl or 4-methylphenyl
radical.
A tetralkylphosphonium chloride is preferably used.
Tetrabutylphosphonium chloride, commercially available and particularly
efficient, is more especially preferred.
It will be appreciated that certain palladium compounds such as PBu.sub.r
PdCl.sub.3 may constitute both a source of palladium and a means for
introducing at least a fraction of the quaternary onium chloride in the
sense described above.
As indicated above, the process according to the present invention may be
carried out using an alkali metal or alkaline earth metal compound as an
ionic chloride. Exemplary such chlorides are LiCl and CaCl.sub.2, with
LiCl being the preferred.
It is of course possible to use a mixture of inorganic chlorides and/or of
quaternary onium chlorides.
In general, the amount of ionic chloride to be employed in the reaction
mixture will be such that the Cl.sup.- /Pd molar ratio is greater than or
equal to 1, this ratio having no upper limits other than by reason of
economic constraints and/or difficulties of handling of the reaction
mixture.
Said molar ratio preferably ranges from 3 to 100.
The reaction mixture may, if appropriate, contain an organic diluent or
solvent. When it is desired to carry out the reaction in the presence of a
diluent or solvent, polar, aprotic, basic or nonbasic solvents are used.
Nitriles such as acetonitrile are exemplary aprotic, nonbasic polar
solvents which are suitable for the process of the invention.
When only alkali or alkaline earth metal chlorides are used, it is
advantageous to conduct the reaction in a polar, aprotic and preferably
basic solvent.
By "aprotic and basic polar solvent" are intended compounds of formula
(VI):
##STR2##
in which R.sub.a, R.sub.b and R.sub.c, which may be identical or
different, are each an alkyl radical, a cycloalkyl radical, an aralkyl
radical or a monocyclic aryl radical having up to 10 carbon atoms, with
the proviso that two of the radicals R.sub.a, R.sub.b or R.sub.c may
together form a single divalent radical --(CH.sub.2).sub.y --, wherein y
is an integer ranging from 3 to 12, and with the further proviso that
R.sub.a may also be a radical
##STR3##
in which R.sub.d and R.sub.c, which may be identical or different, are
each an alkyl radical having up to 4 carbon atoms.
Exemplary such solvents include tetramethylurea, N,N-dimethylacetamide,
N,N-diethylacetamide, N,N-dicyclohexylacetamide, N,N-dimethylpropionamide,
N,N-diethylpropionamide, N,N-diethyl-n-butyramide, N,N-dimethylbenzamide,
N,N-dicyclohexylbenzamide, N,N-diethyl-m-toluamide, N-acetylpyrrolidine,
N-acetylpiperidine, N-(n-butyryl)piperidine, N-methyl-2-pyrrolidone,
N-ethyl-2-pyrrolidone, N-methyl-2-piperidone and
N-methyl-epsiloncaprolactam.
N-Methyl-2-pyrrolidone is particularly suitable for carrying out the
process of the invention.
When a solvent is used, the amount thereof is at least 10% by volume of the
reaction mixture; good results are obtained when on the order of 20% to
90% by volume of solvent is employed.
It is generally possible to conduct the reaction in liquid phase at a
temperature ranging from 50.degree. to 180.degree. C., preferably from
80.degree. to 150.degree., under a carbon monoxide pressure which is
greater than or equal to 20 bar and preferably less than or equal to 250
bar.
Preferably, the carbon monoxide pressure will range from 90 to 180 bar.
Inert gases such as nitrogen, argon or carbon dioxide may be present in
addition to the carbon monoxide.
Upon completion of the reaction or of the time permitted for the reaction,
the desired diester is recovered by any suitable means, for example by
extraction and/or distillation.
In order to further illustrate the present invention and the advantages
thereof, the following specific examples are given, it being understood
that same are intended only as illustrative and in nowise limitative.
EXAMPLES 1 to 5: Control Tests (a) to (d)
The following materials were introduced into a 20-cm.sup.3 stainless steel
(Hastelloy B2) autoclave, purged with argon beforehand:
(i) 8.7 mmol of 1,2-dimethoxy-3-butene;
(ii) 1.66 mg-at. of palladium in the form of PdCl.sub.2 ;
(iii) 6 mmol of ionic chloride; and
(iv) if appropriate, 10 cm.sup.3 of solvent.
The autoclave was closed hermetically, placed in an agitating oven and
connected to the pressurized gas supply. The reactor was purged cold with
carbon monoxide and heated to 95.degree. C. The pressure was then adjusted
to 140 bar. After the reaction, the autoclave was cooled and degassed.
The reaction mixture was then analyzed by gas phase chromatography.
The particular reaction conditions and the results obtained are reported in
Table I below, in which t denotes the reaction period at temperature, HD
(%) denotes the molar quantity of methyl 3-hexenedioate formed per 100
moles of 1,2-dimethoxy-3-butene charged, and DC (%) denotes the degree of
conversion of 1,2-dimethoxy-3-butene.
TABLE I
______________________________________
Ionic t DC 3HD
Example chloride Solvent (h) (%) (%)
______________________________________
1 PBu.sub.4 Cl
none 6 100 80
2 PBu.sub.4 Cl
NMP 6 100 92.5
3 LiCl NMP 6 100 86
4 NMe.sub.4 Cl
NMP 6 100 82
5 DMICl NMP 6 100 91
a none ethanol 6 100 3
b none acetonitrile
6 37 8
c none NMP 6 57 9
d none p-DCB 6 100 38
______________________________________
DMI Cl = N,Ndimethylimidazolium chloride
NMP = Nmethyl-2-pyrrolidone
pDCB = paradichlorobenzene
EXAMPLES 6 AND 7
The following materials were introduced into a 125-cm.sup.3 stainless steel
(Hastelloy B2) autoclave, purged with argon beforehand:
(i) 25 mmol of 1,2-dimethoxy-3-butene;
(ii) 5 mmol of palladium in the form of PdCl.sub.2 ;
(iii) tetrabutylphosphonium chloride; and
(iv) if appropriate, 30 cm.sup.3 of solvent.
The autoclave was then closed and the procedure described in Examples 1 to
5 was repeated (t=95.degree. C.; p=140 bar).
The particular reaction conditions and the results obtained are reported in
Table II below:
TABLE II
______________________________________
PBu.sub.4 Cl t DC 3HD
Example
mmol Solvent (h) (%) (%)
______________________________________
6 5 acetonitrile
8 96 72
7 27 none 8 99 80
______________________________________
EXAMPLES 8 and 9
The procedure of Example 7 was repeated in the autoclave according to the
above technique, on a charge modified as follows:
(i) a mixture of 1,4-dimethoxy-2-butene (1,4-DMB) and of
1,2-dimethoxy-3-butene (1,2-DMB) was introduced,
(ii) 19 mmol of PBu.sub.4 Cl were introduced.
The particular reaction conditions and the results obtained are reported in
Table III below:
TABLE III
______________________________________
1,4-DMB 1,2-DMB t 3HD
Example mmol mmol (h) (%)
______________________________________
8 18.5 8 4.8 65
9 8 17.5 5.7 74
______________________________________
In these two tests, the conversion of the dimethoxybutenes was complete.
While the invention has been described in terms of various preferred
embodiments, the skilled artisan will appreciate that various
modifications, substitutions, omissions, and changes may be made without
departing from the spirit thereof. Accordingly, it is intended that the
scope of the present invention be limited solely by the scope of the
following claims, including equivalents thereof.
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